Radio tuning condenser



Feb. 4, 1941. R J J. STARR 2,230,550

RADIO TUNING CONDENSER Filed Sept. 18,, 1937 Patented F e5. '4, 1941 UNITED STATES,

PATENT OFFICE Application September 18, 1937, Serial No. 164,452 In Canada Nor'cmber'z, 1936 Claims. (or 115-4415) The object of my invention is to provide a tuning-condenser having separate and independent means for changing the total capacity from a maximum stage into many stages of lower total capacity and having means for manipulation located on the outside of a radio receiver and being adapted to serve the same purpose as a great number of condensers constructed in the usual way. One species consists of one stator plate and one semi-circular rotor plate, which is secured to a rotatable shaft-one half revolution of which changes the area of opposing surfaces from zero to full opposition of the two plates, and it has separate means for adjusting the distance between the plates for changing the total capacity. Any number of such condensers may be combined to form a gang condenser. Such a gang condenser is not a separate invention, for it is Just several single condensers, which are used in different circuits, but are operated by the same means of manipulation, and it is only one of the ways in which the condenser may be employed. In a gang condenser one extra rotor plate is required for equalisation of capacity in all .the condensers of the gang, or instead, one more condenser than there are circuits may be inserted in the gang, and the stator plate in that condenser may be removed or left, as it makes no difference either way.

I attain these objects of my invention by the mechanism illustrated in the accompanying drawing, which is shown in Figs. 1 to 6, inclusive:

Fig. 1 is a side elevation of a single condenser.

Fig. 2 is a broken out part of the front elevation of the front panel of a receiver showing the dial and two pointers.

Fig. 3 is a side elevation of a gang condenser, which is composed of a pluraltiy of single condensers and one extra rotor plate as was mentioned previously.

Fig. 4 is an elevation on section line 4-4 of Fig. 3.

Fig. 5 is a vertical section in larger scale through part of the rotor shaft and the spacer tubing.

Fig. 6 is a fractional .part in larger scale showing construction of the rods in a gang condenser, which hold and space the front and rear supports of a condenser and supporting the stator platw; the rods are broken open for showing how the rods are insulated from the stator plates and showing the insulating spacers between the stator .plates. The spacers between the rotor plates in a gang condenser are similar to those separating stator plates, but they may be metallic so as to electrically connect all the rotor plates to the shaft, which is terminal for all, but dielectric spacers may be used if provision is made .to otherwise electrically connect all rotor plates to the shaft.

Similar numerals and letters refer to similarparts throughout the several views.

The condenser species shown in Figs. 1 to 6, inclusive, has a front support 2a and a rear support 2b preferably of insulating material, and they are held rigidly in parallel position by a plurality of rods 3. These rods may be metallic when used in a single condenser (Fig. 1), in which case, any one of the rods may serve as a terminal for the stator plate, but when used in a gang condenser (Fig. 3), they must be of insulating material, or else, covered by insulating maten'al such as tubing 4-and have insulating separators of insulating material-such as separators 5between all the stator plates 1, so as to separate and insulate each of the stator plates belonging to single condensers composing the gang from all the others (Fig. 6). The rotor shaft 6 carries one rotor plate 8 in each single condenser and one extra rotor plate 8 so as to equalize the capacity in all the condensers composing the'gang. The shaft 6 should be partly threaded at the front end. The separators 8 between rotor plates may be metallic so as to electrically connect them and the plates to shaft 6, which serves as terminal, but they may be of insulating material if means are provided to electrically connect each rotor plate 8 to shaft 6. An indicating pointer I0 is adjustably secured to the front end of shaft 8 by means of a setscrew-shown in Figs. 1 and 3 but not markedfor indicating on a scale on dial 11 the degree of rotation of shaft 6 and plate or plates 8 and, thus, indicate the area of opposing surfaces of rotor and stator plates, and this pointer may be adjusted so as to serve as a stop. The shaft 6 passes through a spacer tubing II with a snug but rotatable fit, and it is hindered from sliding endwise in spacer tubing it by the removable and adjustable stops I0 and i2. The spacer tubing II is partly threaded on its outside for co-operation with the treads in a bushing 26 secured to the front support 211 so that, when spacer H is rotated, it will move longitudinally in or out and carries shaft 6 and rotor plates 8 with it in a uniform longitudinal movement for regulation of the space between rotor plates 8 and stator plates 1 and, thus, change the total in a; gang condenser,

. have done in the past.

capacity of the condenser .to any total capacity stage that may be required for efllcient co-operation with different inductances suitable for different wave bands, and the total capacity, whatever it may be,/is divided by rotation of shaft 8 and plates 8' for change of the area of opposing surfaces of rotor and stator plates and, thus, tune incoming signals in resonance in different wave bands. It is well known, that a condenser must act in conjunction with an inductance to be of any value, but inductances are not included in this my present invention, though they may be mentioned for better understanding of my invention. The adjustable stop I2 on shaft 8 may serve as an abutment for rotor plates 8 on shaft 8 and said shaft carries cogwheel I3 which is part of a slow movement device for rotation of said shaft, the end of which is threaded for nut I4, which presses wheel I3 against separators 8 on the shaft, for holding the wheel I3 and plates 8 in a rigid position between nut I4 and abutment I2. For the purpose of rotating spacer II, there is a cogwheel I5, part of another slow movement device, mounted on spacer II, which also carries a double ended pointer I8 removably secured to the front end of spacer I I by means of a set-screw (shown in Figs. 1 and 3, .but not marked) for the purpose of indicating on a scale on dial I! the degree of rotation of said spacer and thus, concurrrently, indicate the distance between rotor and stator plates and the consequent total capacity of the condenser at diflerent stages of rotation of spacer II. The dail I1 is calibrated in a plurality of semi-circular scales for the two pointer mentioned and is secured in suitable location by bolts I8 or other suitable means. A rotatable shaft I9 passes through the condenser from front .to rear and extends through the front .panel 2I of a receiver, where it carries knob 28 for manipulation purpose, and, at the rear end, it carries sprocket 22, which meshes with cogwheel I3 for rotation of shaft 8 and rotor plates 8. There is a sleeve 28 mounted on shaft l9 with an independent rotatable fit and, on its front end, outside of the panel 2|, it is provided with knob 24 for manipulation purpose, and, on its rear end, it carries sprocket 25, which meshes with the cogwheel I5 for rotation of spacer II. The two slow movement devices described are not claimed by me, as I may use other slow movement devices, or, I may set set pointer I6 at a desired place by hand and provide front end of shaft 6 with a knob for direct manipulation and rotation of said shaft, which I The bushing 28, mentioned above, is secured to the front support 2a in an adjustable manner by means of threads on its outside and clamping nut 21. On its inner surface it is provided with threads for co-operation with the threads on spacer II for the purpose of adjusting the distance between rotor and stator plates and, thus, determine the stage of total capacity of the condenser as previously explained. 1

The resistance of the slow movement devices will prevent shaft 8 from rotating with the spacer as well as prevent spacer from rotating with the shaft, and, if there is no slow movement device used, then some other frictional device must be used for the required resistance.

28 is a dielectric rod removably secured at one end to the front support 2a and, at the other end to rear support 21) in such location as .to confine the rotor plates, or plate, to one half revolution. (Location shown in Fig. 4 only.)

38 is solid dielectric material attached to the opposing surface of stator plates, as shown, but may -be attached to rotor plates if preferred, for the purpose of preventing sparking between rotor and stator plates, as well as, for increase of capacity when low frequencies are tuned in. All stator plates have individual terminals for connection in different circuits, and all rotor plates have shaft 8 as a common terminal. The leads I are shown, but not marked. They may be flexible leads.

I do not claim any fixed rule for calibrating scales on the dial, as that is left for the manufacturer to decide what will suit different radio receivers, but I suggest that'there be two or more semi-circular scales for the two ends of the pointer I8 for indicating capacity, in mmf., and another scale for pointer I0 divided in points, so that one scale will serve for all frequency bands; for graduations indicating kilo-cycles and mega-cycles or meters would be too crowded and complicated on the dial. I suggest, instead, that 'a list of the different coils be attached near the dial, showing the setting of pointer 16 and the frequencies included in the band covered by each coil.

To operate the condenser:

The pointer I8 is set at a point on the dial, which indicates the total capacity suited to the inductance coil in the circuit at the time. The shaft 6 and rotor plates (or plate) are then rotated for change area of opposing surfaces of rotor and stator plates and, thus, tune in signals of all frequencies in the band covered by the coil and condenser. If a different frequency-band is desired, pointer I6 is reset to indicate the proper total capacity required for another inductance, and shaft 8 with rotor plates (or plate) is rotated for tuning in all frequencies in the new band, etc.

What I claim is:

1. A radio tuning condenser having front and rear supports held in position by a plurality of rods, one single stationary plate supported on said rods and having solid di-electric material secured to the plate, a bushing mounted in the front support mentioned and having threads on its inner face, a spacer tubing having threads co-operatlng with the threads in the bushing for adjustment of distance between rotor and stator plates for desired value of the total capacity, a double ended pointer on the front end of the spacer tubing, a rotatable shaft carrying one single semi-circular rotary plate and passing through the spacer tubing mentioned with a rotatable fit, stops on the shaft preventing it from sliding endwise in the spacer tubing, a pointer on the front end of the shaft, manipulationmeans for rotation of the spacer tubing, manipulation-means for rotation of the shaft mentioned, and means for connection in circuits.

2. A gang condenser for tuning a. plurality of separate radio circuits simultaneously and composed of a plurality of single condensers each one of which consisting of one stator plate and one rotor plate, the stator plates of all the single condensers mounted on the same supports and each one of them insulated from all the others, the rotor plates of all the single condensers assembled on the same partly threaded rotatable rotor shaft for simultaneously regulating the area of opposing surfaces in each single condenser by rotation of said shaft, a rotatable spacer-member for regulating the space between rotor and stator plates of each single condenser simultaneously by causing longitudinal movement of rotor shaft and plate by rotation of spacer-member for change of the total capacity of the condenser and adjustable and removable stops are provided for hindering the rotor shaft from sliding longitudinally in the spacer member, means for manipulation and rotation of the rotor shaft and plate, means for independent manipulation and rotation of the spacer-member mentioned, suitable supports for all parts, suitable means for connection of the single condensers in different circuits, substantially as described.

3. A gang condenser composed of a plurality of single condensers for tuning different and separated radio circuits in a radio receiver simultaneously by the same manipulation-means common to all the single condensers each one of which consists of one stator plate mounted on a plurality of supporting rods common to the stator plates of all the single condensers but each one insulated from all the others, dielectric material on the stator plates for hindering sparking as well as for increase of capacity, one rotor plate in each single condenser, the rotor plates of all the single condensers mounted on the same partly threaded rotor shaft for tuning all the circuits simultaneously, a spacer-tubing partly thre-arer on. its outside and adapted for passage of the rotor shaft through the inside with a rotatable fit, a bushing having threads on its inner surface co-operating with the threads on the spacer-tubing for moving the spacer-tubing and rotor shaft and all the rotor plates longitudinally for the purpose of varying the space between rotor and stator plates in each single condenser and thus change the total capacity simultaneously in each single condenser when spacer-tubing is rotated, a pointer adjustably secured at the front end of the rotor shaft for indicating on a dial the degree of rotation of the shaft and the area of opposing surfaces of rotor and stator plates in each and all the single condensers, a double-ended pointer removably secured at the front end of the spacertubing for indicating on a dial the distance between the rotor and stator plates in each of the single condensers and thus the total capacity of each single condenser, suitable means for manipulation and rotation of shaft and rotor plates, suitable means for manipulation and rotation of the spacer-tubing, suitable supports for all parts, and terminals for connection in the different circuits tuned by this gang condenser, substantially as described.

4. A variable and adjustable tuning condenser for radio consisting of and including, a front support and a rear support held in proper position by a plurality of rods which also serve as supports for one stator plate of approximately triangular shape and having solid dielectric material attached to its opposing surface for the purpose of increasing capacity as well as for preventing sparking between rotor and stator plates, one rotor plate mounted on a rotatable rotor shaft for variations of the area of opposing surfaces of rotor and stator plates and thus dividing the total capacity between said plates in suitable quantities and a stop-rod of dielectric material is provided for confining the rotation of the rotor shaft and plate to one half revolution in either direction, a spacer tubing having threads on its outside for co-operation with threads in a bushing for adjustment of total capacity and being adapted for passage of the rotor shaft through its central open space with a snug but rotatable fit, adjustable and removable stops on the shaft for hindering the same from sliding endwise in the spacer tubing, a bushing adJusta-bly secured to the front support mentioned and having threads on its inside for co-operation with the threads on the spacer tubing for regulation and adjustment of the magnitude of the space between rotor and stator plates by rotation of the spacer tubing for change of the total capacity of the condenser so as to make the condenser efllcient for use in numerous and different frequency bands, a pointer adiustably mounted on the front end of the rotor shaft for indicating on a dial the degree of rotation of said shaft and rotor plate and thus indicating the area of opposing surfaces of rotor and stator plates for tuning in resonance signals in numerous and different frequency bands determined by the degree of rotation of the spacer tubing, 9. double ended pointer removably secured on the front end of spacer tubing for indicating on a dial the degree of rotation of spacer tubing and thus indicating the stage of total capacity of the condenser, a dial suitably supported and calibrated in scales suitable for the two pointers mentioned, suitable means for rotation of the rotor shaft by manipulation, separate and independent means for rotation of spacer tubing by manipulation, suitable terminals for connection in radio circuits, and suitable supports for all parts of the condenser, substantially as described.

5. A gang condenser having a front support and a rear support held in rigid and parallel position to each other by a plurality of insulated rods, a plurality of single condensers each one of which consists of one stator plate having dielectric material attached to its opposing surface for increase of capacity as well as for preventing sparking between stator and rotor plates and each one of the stator plates is insulated from all the others by insulating spacers between them as well as by the insulation on the shafts mentioned on which they are all mounted, one more rotor plates in number than the number of stator plates of all the single condensers so as to equalize the capacity in all the single condensers and all .the rotor plates are mounted on the same rotatable rotor shaft for simultaneous change of area of opposing surfaces of rotor and stator plates in each and all of the single condensers and having metallic spacers between the rotor plates and all of them are electrically connected to the rotor shaft which serves as terminal for the rotor plates, a bushing adjustably secured to the front support and having threads on its inside, a rotatable spacer tubing passing through the bushing and having threads on part of its outside cooperating with the threads in the bushing for moving spacer tubing longitudinally by rotation of the same and being adapted for passage of the rotor shaft through its central space with a snug but rotatable flt and adjustable stops on the shaft prevent it from sliding endwise in the spacer tubing so that when spacer tubing is rotated shaft and rotor plates are moved longitudinally for change of distance between rotor and stator plates in each single condenser and thus cause change of the total capacity in all the single condensers simultaneously and equally and this total capacity whatever it may be is divided in suitable quantitles by rotation of rotor shaft and all the rotor plates of all the single condensers for simultaneous variation of area of opposing surfaces of rotor and stator plates in each of the condensers composing the gang, a pointer adjustably secured on the front end of the rotor shaft so as to indifor manipulation and rotation of the rotor shaft. independent means for manipulation and rotation of the spacer tubing, suitable supports for all parts, suitable terminals tor connection radio circuits, substantially as described.

ROBERT J. J. STARR. 

